1. Field of the Invention
The invention relates in general to a wrench having two driving stems pivotally connected with each other. More particularly, this invention relates to a hex key type or Allen wrench having two individual driving stems pivotally connected with each other.
2. Description of the Related Art
A conventional wrench, for example, an Allen wrench, used for gripping and turning or twisting the head of a bolt, a cap screw, a nut, a pipe, or the like commonly comprises a one-piece L-shape metal with one end used as the driving stem and the other end used as a handle.
In U.S. Pat. No. 5,943,925, Huang discloses a tool having a foldable structure. The foldable structure disclosed by Huang comprises a coupler pivotally coupled between a driving stem and a handle. Applying the foldable structure to the Allen wrench, the driving stem can be folded in parallel with the handle, that is, with a zero angle relative to the handle. This results in a more compact space for storing the tool. In Huang, with respect to the handle, the driving stem can be rotated from an angle of zero degrees to an angle of 180 degrees. While turning a bolt in a limited space, for example, around the boundary of two perpendicularly joint planes, the handle of the Allen wrench adopting the foldable structure disclosed by Huang can only be turned between zero degrees to 180 degrees along a surface perpendicular to the driving stem. When a half circle of the turning action is complete, the user has to disengage the wrench from the bolt. By repositioning the handle to the original point of the turning action, the turning action is repeated until the bolt is fastened as required.
In other words, while tightening/untightening a screw, a bolt or a nut in a plane with a limited degree of freedom, a user may need to repeat engaging and disengaging the driving stem to reposition the handle. Moreover, using this conventional structure, there is only one end of the wrench that can be used as the driving tool while the other end is used as a handle only. When a different torque is required, or a screw, a bolt or a nut with different depth is to be driven thereby, a different driving stem has to be connected and reassembled.
The invention provides a wrench having two driving stems pivotally connected with each other. One of the driving stems has a female fork joint protruding from the main stem with a hole at the center thereof. The other driving stem has a male connecting joint protruding form the axial center of the main stem. The male joint and the female joint are engaged with each other via a connector such as a roll pin. Therefore, without using an additional hinge or other mechanical coupler, these two driving stems are pivotally connected with each other. One of these two pivotally connected driving stems flips from an angle of about 90 degrees to an angle of about 270 degrees relative to the other.
Thus arranged, one of the driving stems used as a handle can flip with an angle from about 90 degrees to about 270 degrees with respect to the other of the driving stems used for driving a screw, a bolt or a nut. Therefore, when the rotation of the handle is obstructed, the handle can be lifted up or down to perform fastening or removing. The specific flipping angle of the handle actually depends on the distance between the driving stems. That is, the handle can also be flipped from an angle less than 90 degrees to an angle larger than 270 degrees.
The applicability of the wrench structure provided by the invention is also applicable for driving a socket head screw, bolt or nut in a space with limited degree of freedom, for example, in the situation that the rotation of the handle is obstructed by the presence of an object. For example, while driving a socket head cap screw on a plane with a second plane protruding nearby, the screw is engaged with the driving stem, and the handle is turned to drive the driving stem, so as to thread/unthread the screw. Being obstructed by the protruding object, the rotating range of the handle is limited within a certain angle along a surface parallel to the first plane. When the rotating action of the handle is from one end to the other, that is, from an angle of zero degree to the certain degree along the surface, the user does not need to disengage the driving stem from the nut. Instead, the user can simply flip the handle to the other end, that is, from the angle of 90 degrees to 270 degrees relative to the driving stem, and carry on driving the screw.
In addition, with the structure of two driving stems pivotally connected together, one may choose either one of the driving stems as a handle, and the other driving stem to engage and drive an object, for example, a screw, a nut, a bolt or the like. When an object with a different depth is to be engaged and driven, or when a different torque is required, one may interchange the functions of these two driving stems. Further, in certain circumstances, the user may choose to align the two stems with each other (at zero degree angle) and drive the object by applying a socket wrench to the free end of the stem opposite the driving stem.
Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.